ET Metric Coarse HS Ground Thread Type A, C & D ETCTT-8mm* 1.25mm have dia and pitch 8mm* 1.25mm have an odd number of lands with alternate teeth in the thread helix removed. The removal of every other tooth helps to break the chip and allows a greater supply of lubrication to reach the cutting teeth, reducing the incidence of torn threads. Ideal for tapping non ferrous metals and low carbon steel; as well as use in titanium and high hardness alloys.